Discrimination of Cocoa Beans According to Geographical Origin by Electronic Tongue and Multivariate Algorithms

Electronic tongue as an advanced and novel emerging technology has been successfully utilized for the rapid identification of cocoa beans according to their geographical locations. Seven categories of cocoa beans from Ghana were used in this experiment. Electronic tongue system was used for data acquisition while three pattern recognition methods were applied comparatively to build discrimination model. The performances of the models were cross-validated to ensure its stability. Experimental results revealed that Fisher’s discriminant analysis (FDA) is better than principal component analysis (PCA) for visualizing the cluster trends. K-nearest neighbor (KNN) model was slightly better than FDA model at an optimal performance of 100 % in the training set and 98.8 % in prediction set. Overall, support vector machine (SVM) was superior to both FDA and KNN with 100 % discrimination rate in both the training and prediction set at five PCs. This finding proves that electronic tongue technology coupled with SVM technique can rapidly, accurately, and reliably discriminate cocoa beans for quality assurance management.     

Novel Prediction of Total Fat Content in Cocoa Beans by FT-NIR Spectroscopy Based on Effective Spectral Selection Multivariate Regression

Total fat content is a major quality parameter that chocolate manufactures consider when selecting cocoa beans. This paper attempted the feasibility of measuring total fat content in cocoa beans by using Fourier transform near-infrared (FT-NIR) spectroscopy based on a novel systematic study on efficient spectral variables selection multivariate regression. After the efficient spectra interval selection by synergy interval partial least squares (Si-PLS), the data were treated with support vector machine regression (SVMR) leading to synergy interval support vector machine regression (Si-SVMR). Experimental results showed that the model based on the novel Si-SVMR algorithm was superior to the others. The optimum results were assessed by root-mean-square error of prediction (RMSEP) and correlation coefficient (R _pre) in the prediction set. The performance of Si-SVMR model was RMSEP?=?0.015 and R _pre?=?0.9708. This study has demonstrated that the total fat content in cocoa beans could rapidly be predicted by FT-NIR spectroscopy and Si-SVMR technique. The novel strength and accuracy of Si-SVMR in contrast to other multivariate algorithms has been derived.     

Sequencing and Identification of Different Salmonella Species in Cocoa Beans Treated with Gamma Irradiation

Gamma irradiation is an effective way to eliminate the bacterial load in cocoa beans. During harvesting these are exposed to various factors of contamination. The aim of this study was to analyze the effect of gamma irradiation on the presence of Salmonella spp considered a microbiological risk in chocolate. Cocoa samples (n = 31) were treated with three doses of gamma irradiation (2, 3 and 5 kGy) besides a control sample without irradiation. The PCR method revealed 22 bacteria (n = 124) with Salm3-Salm4 amplified. The DNA sequencing method confirmed the presence of two isolates who belong to Salmonella spp. and 20 belonging to Klebsiella sp and Enterobacter sp. These results were retrieved from the control samples and irradiation 2kGy, while radiation 3 to 5 kGy no growth of microorganisms.     

多波长线性回归光度法同时测定食品中钙镁

在pH =8 .8的硼砂缓冲溶液中 ,三氯偶氮氯膦分别与Ca2 + 和Mg2 + 形成稳定的配合物。用多波长线性回归光度法同时测定钙、镁。合成样品中钙和镁的回收率分别为 94%～ 10 5 %和 95 %～ 10 4%。该方法应用于食品中钙、镁含量的测定 ,结果满意     

Organic Acids in Cider with Simultaneous Inoculation of Yeast and Malolactic Bacteria: Effect of Fermentation Temperature

Analysis of major organic acids in cider was performed by HPLC after simultaneous inoculation of selected yeast and malolactic bacteria in apple juice. Fermentations were carried out at two different temperatures, 15°C and 22°C, in order to compare the composition of the products obtained. Consumption of malic acid was affected by fermentation temperature, although in both cases this acid was fully metabolised. At both temperatures tested, an important decrease in lactic acid was observed after completion of malic acid degradation, along with formation of high levels of acetic acid.     

Nondestructive Prediction of Tilapia Fillet Freshness During Storage at Different Temperatures by Integrating an Electronic Nose and Tongue with Radial Basis Function Neural Networks

This study developed principal component analysis and radial basis function neural networks (PCA-RBFNNs) for predicting freshness in tilapia fillets stored at different temperatures by integrating an electronic nose and electronic tongue. Total volatile basic nitrogen (TVB-N), total aerobic counts (TAC), and K value increased at 0, 4, 7, and 10 °C, while sensory scores decreased significantly. The electronic nose and tongue acquired the volatiles and dissolved chemical compounds in the stored samples. Gas chromatography-mass spectrometry (GC-MS) verified the changes in gas species and contents in fillets stored for different periods of time at different temperatures. PCA-RBFNNs based on data fusion were developed and presented good performance for prediction of TVB-N, TAC, K value, and sensory score in tilapia fillets. The established PCA-RBFNNs based on feature variables of the electronic nose and tongue is a promising method to predict changes in the freshness of fillets stored from 0 to 10 °C in the cold chain.     

超声萃取-气相色谱/质谱-选择离子监测法同时测定涂布纸中21种邻苯二甲酸酯类增塑剂

以三氯甲烷为萃取溶剂,超声萃取纸品中的邻苯二甲酸酯类增塑剂,提取产物进行气相色谱/质谱-选择离子监测法测定,从而建立了一种同时测定纸品中21种邻苯二甲酸酯类增塑剂的方法。该方法简便快捷、灵敏度高、定性定量准确。该方法的平均回收率为81.98%～106.82%,精密度试验相对标准偏差(RSD)为2.11%～9.75%。DIDP和DINP的检出限分别为2.0、1.0mg/kg,其余各组分的检出限均小于0.4mg/kg。采用该方法对市售涂布纸进行测定,结果在部分涂布纸中检出邻苯二甲酸酯类增塑剂。     

Rapid Simultaneous Screening and Detection of 12 Anticoagulant Rodenticides in Food by Ultra-performance Liquid Chromatography-Triple Quadrupole/Linear Ion Trap Tandem Mass Spectrometry

A rapid analytical method for the simultaneous screening and detection of 12 anticoagulant rodenticides in food samples was established based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method using an ultra-performance liquid chromatography-triple quadrupole/linear ion trap tandem mass spectrometry (UPLC-QTrap-MS/MS). Food samples were extracted and purified with modified QuEChERS method. The 12 anticoagulant rodenticides (warfarin, brodifacoum, difethialone, coumachlor, coumatetralyl, bromadiolone, chlorophacinone, difenacoum, diphacinone, pindone, valone, and flocoumafen) and the internal standard (warfarin-D₅) were separated within 6 min using an ACQUITY UPLC BEH-C18 column (1.7 μm, 2.1 mm × 50 mm) and gradient elution with the mobile phase consisting of 5 mM ammonium acetate formate buffer and acetonitrile. The multiple reaction monitoring-information dependent acquisition-enhanced product ion (MRM-IDA-EPI) scanning was employed for detection. The calibration curves were linear (R ² > 0.99) for all the compounds. The mean recoveries for the 12 analytes at three spiked levels (1× LOQ, 5× LOQ, and 10× LOQ) were in the range of 79.5–113.2% with RSDs of 1.8–13.2%.The limits of detection (LOD) for the 12 rodenticides ranged from 0.01 (warfarin) to 0.05 μg/kg (diphacinone). The limit of quantification (LOQ) for the 12 rodenticides was between 0.02 (warfarin) and 0.10 μg/kg (diphacinone). The developed method was more straightforward, less time and labor intensive, and more sensitive, selective, and accurate for screening multiple anticoagulant rodenticides, and it was successfully used in several poisoning cases.     

Analysis of Volatile Compounds in Hullessbarley by Simultaneous Distillation and Extraction Coupled with GC-MS

建立了同时蒸馏萃取-气相色谱/质谱联用技术（SDE-GC/MS）分析青稞中挥发性化合物的方法,获得26种组分的定性和定量结果。采用这一技术对瓦蓝、肚里黄、白青稞、黑老鸭等4种青稞酒原料进行分析,结果表明,不同青稞品种间化合物种类接近又各具特点。本研究还对同时蒸馏萃取技术参数优化、青稞中主要挥发性组分进行了分析研究。     

同时蒸馏萃取技术分析酿酒原料青稞中挥发性化合物的研究

建立了同时蒸馏萃取-气相色谱/质谱联用技术（SDE-GC/MS）分析青稞中挥发性化合物的方法,获得 26 种组分的定性和定量结果。采用这一技术对瓦蓝、肚里黄、白青稞、黑老鸭等四种青稞酒原料进行分析,结果表明不同青稞品种间化合物种类接近又各具特点。本研究还对同时蒸馏萃取技术参数优化、青稞中主要挥发性组分进行了分析研究。     

Simultaneous determination of organophosphorus pesticides in cruciferous vegetables by dual-column GC with pulsed FPD and FTD

We evaluated simultaneous analytical methods for organophosphorus pesticides in cruciferous vegetables by gas chromatography (GC). Firstly, 36 pesticides were selected on the basis of monitoring data (April 1996-March 2003) in Aichi Prefecture. A sample was extracted with acetonitrile and the acetonitrile layer was separated by salting-out. The extract was cleaned up with gel permeation chromatography (GPC), and then with a tandem silica-gel/PSA mini-column. The test solution was subjected to dual-column GC equipped with a pulsed FPD (P mode, Rtx-OPPesticides column) and a FTD (Rtx-OPPesticides 2 column). Organophosphorus pesticides in such sulfur-rich matrices as cabbage and radish were determined without any serious interfering peaks on the pulsed FPD chromatograms after diluting the extracts 10- to 20-fold (0.25-0.5 mg/L of sample). The method was applied to cruciferous vegetables to demonstrate its usefulness in routine analysis.     

Simultaneous Determination of Nitrate and Nitrite in Fish Products with Improved Sensitivity by Sample Stacking-Capillary Electrophoresis

A fast and reproducible method for the simultaneous determination of nitrate and nitrite ions in canned fish samples by capillary zone electrophoresis has been developed. The sensitivity of the method was increased by applying a sample stacking technique. Optimal separation conditions were selected as 30 mmol L^?1 formic acid and 30 mmol L^?1 sodium sulfate at a pH of 4.0. The separation of nitrate and nitrite ions was achieved within 2.5 min. The limits of detection obtained at a signal-to-noise ratio of 3 for nitrate and nitrite were 0.55 and 0.82 μmol L^?1, while the relative standard deviations of intra-day corrected peak areas were 0.99 and 2.74 %, respectively. Recovery values ranged between 88.7 and 104 % for both ions. The method was successfully applied to canned fish samples, namely tuna, mackerel and sardine.     

离子色谱双通道自动进样同时分析瓶装水中阴阳离子

建立了一种离子色谱双通道自动进样同时分析检测瓶装水中阴阳离子的方法。所测离子包括消毒副产物溴酸盐,常规阴离子F-、Cl-、NO2-、Br-、NO3-,SO4^2-以及常规阳离子Na＋、K＋、Mg^2＋、Ca^2＋。其中溴酸盐能够准确定量到5μg/L,远远低于国家标准中10μg／L的限量要求,完全可以满足检测需求。使用自动进样系统实现阴阳离子同时进样分析,简便快捷,无需变换系统,一次性完成阴阳离子分析测定。此方法用于实际样品的检测获得满意结果,可用于瓶装水的批量检测。     

Simultaneous determination of ascorbic and dehydroascorbic acids in vegetables and fruits by liquid chromatography with tandem-mass spectrometry

This work describes an analytical method using liquid chromatography coupled with tandem-mass spectrometry (LC–MS/MS) with triple quadrupole in selective reaction monitoring mode for the simultaneous determination of ascorbic acid (AA) and dehydroascorbic acid (DHAA) in pepper, tomato, orange and lemon. The negative ion mode of ESI and MS/MS transitions of m/z 173→143 and m/z 173→71 were used for AA and m/z 175→115 and m/z 175→87 for DHAA. All the validation parameters were found to be within the range of acceptance for both compounds. Different matrix effects were observed in the studied vegetables and samples were quantified by the standard addition approach. The proposed method was suitable for simultaneously determining AA and DHAA with no need for oxidation/reduction or derivatisation steps. The main advantages of this method are its simplicity (little sample preparation), speed (total analysis time does not exceed 5 min) and excellent sensitivity (limits of detection (LODs) of 13 and 11 ng/ml for AA and DHAA, respectively).     

Simultaneous determination of dichlorvos, trichlorfon and naled in fruits and vegetables by liquid chromatography with tandem mass spectrometry

A method for simultaneous determination of Dichlorvos (DDVP), Trichlorfon (DEP) and Naled (BRP) in fruits and vegetables by liquid chromatography with tandem mass spectrometry (LC/MS/MS) was developed. Pesticides were extracted with ethyl acetate together with phosphoric acid and anhydrous sodium sulfate, followed by an ENVI-Carb cartridge cleanup. Phosphoric acid prevented BRP from being converted to DDVP during extraction of pesticides from the sample. When the sample was dissolved in acetonitrile in a silanized glass vial, BRP and DEP remained intact. Mass spectral acquisition was performed with a TurbolonSpray (ESI) interface in the positive mode by applying multiple reaction monitoring. In LC separation, an ODS column was used with acetic acid-ammonium acetate-methanol as a mobile phase. Recoveries from 8 fruits and vegetables at the fortification level of 0.1 microg/g were 75.0-91.8% for BRP, 70.2-88.9% for DDVP, and 77.3-92.1% for DEP. The detection limits of BRP, DDVP and DEP were 1, 2 and 2 ng/g, respectively.     

Simultaneous spectrophotometric determination of caffeine and theobromine in Iranian tea by artificial neural networks and its comparison with PLS

In order to determine the amount of caffeine and theobromine, spectrophotometry was used as a simple, rapid and economical method. Because of severe overlapping between these components, artificial neural network was used. The 230–300 nm spectral window with 1 nm interval was used for data acquisition. An artificial neural network (5-5-3) with linear transfer function between input-hidden and hidden-output layers was trained and applied for prediction of concentration of these methylxanthines in four Iranian tea samples. The model was compared with PLS modeling method. HPLC technique was used as a standard method.     

免疫亲和柱-高效液相色谱法同时检测谷物中T-2毒素和HT-2毒素含量

建立了免疫亲和柱净化-柱前化学衍生-高效液相色谱荧光检测器同时检测谷物中T-2毒素和HT-2毒素的方法。样品经溶剂[V(甲醇)∶V(水)=80∶20]提取,通过免疫亲和柱净化(IAC),以氰酸蒽(1-AN)为衍生化试剂、4-二甲基氨基吡啶(DMAP)为催化剂进行衍生,以ZORBAX Eclipse XDB苯基柱为分离柱,乙腈-水为流动相进行高效液相色谱分离和检测。在0.005⁰.5μg/g内呈良好线性,检出限为0.005μg/g,添加回收率为82.0%0.5μg/g内呈良好线性,检出限为0.005μg/g,添加回收率为82.0%¹08.0%,RSD<15.5%。     

Simultaneous Determination of Seven Plant Growth Regulators in Melons and Fruits by Modified QuEChERS Coupled with Capillary Electrophoresis

A capillary electrophoresis method for the simultaneous determination of seven plant growth regulators including gibberellic acid, abscisic acid, 3-indole acetic acid, 3-indolepropionic acid, 3-indolebutyric acid, 2,4-dichlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxyacetic acid in melons and fruits was established and validated. The samples were ultrasonically extracted with acidified acetonitrile and then dehydrated. The resulting solution was purified with modified QuEChERS method, and then dried-up under weak nitrogen flow, and the residue was redissolved with methanol-water (1:4, v/v) as sample solution. The electrophoretic separation was performed in an uncoated fused-silica capillary with borax buffer (pH 10.5) containing 29% of ethanol as the running buffer. The running voltage was 25 kV with the column temperature of 30 °C. The linear ranges of gibberellic acid, abscisic acid, and 2-methyl-4-chlorophenoxyacetic acid were from 0.10 to 8.0 μg/mL, while the others were from 0.05 to 4.0 μg/mL with the correlation coefficients greater than 0.997. The limits of detection and the limits of quantification of the method were in the range of 1.54–5.76 and 5.12–19.2 μg/kg, respectively. The recoveries of the method ranged from 69.0 to 109% with the relative standard deviations ranging from 2.01 to 15.4%. The proposed method has been successfully applied to the determination of plant growth regulator residues in 15 melon and fruit samples, and gibberellic acid and abscisic acid were detected in the samples.     

Simultaneous analysis of acidulants and preservatives in food samples by using capillary zone electrophoresis with indirect UV detection

Capillary zone electrophoresis with indirect UV detection was developed for the simultaneous analysis of acidulants and preservatives in food samples. When a solution of tris (hydroxymethyl) aminomethane, trimellitic acid and poly (vinyl alcohol) was used as the background electrolyte, the nine acidulants and four preservatives listed in the Japanese Food Sanitation Law were detected within 8 min. The calibration curves plotted from the peak height of each analyte were linear with a correlation coefficient of 0.99. The relative standard deviations (n = 10) of the peak height ranged from 1.2% to 4.7%. The detection limits for these species ranged from 0.6 to 5.3 mg/L at a signal-to-noise ratio of three. The method developed method was applied to the simultaneous analysis of acidulants and preservatives in a wide variety of food samples.